The present invention relates to a syringe having a breakable plunger rod to prevent further use of the syringe after fluid delivery or injection. The present invention also relates to fluid transfer devices having improved needle attaching features and in particular, structure to help prevent the removal of a hypodermic needle assembly from a fluid transfer device such as a hypodermic syringe.
Throughout the world the re-use of hypodermic syringe products which are intended for single-use only is instrumental in drug abuse and in the transfer of contagious diseases. Intravenous drug users who routinely share and re-use syringes are a high-risk group with respect to the AIDS virus. Also, the effects of multiple use are a major concern in some countries where the repeated use of syringe products during mass inoculation programs may be responsible for the spread of many diseases. Syringes are often recycled in developing countries without proper sterilization.
Many attempts have been made to remedy this problem. Some designs involve the inclusion of structure which will allow the destruction or defeating of the syringe function through a conscious act by the user, such as breaking a syringe or one of its components. In addition, there are single-use hypodermic syringes which become incapable of further use automatically upon delivery of the medication without any additional act on the part of the user. Such syringes are taught in U.S. Pat. No. 4,961,728.
With single-use syringes using needle assemblies having a hub attached to a needle cannula there is a need to prevent the removal of the needle assembly after the use of the single-use syringe so that the needle assembly cannot be used again with other syringes. In addition to preventing the removal of the needle assembly, there is also a need for structure which will allow the easy attachment of the needle assembly to the syringe so that the needle assembly may be attached at the time of use and an appropriately sized needle may be used.
A fluid transfer device comprises a barrel having a fluid chamber, a proximal end, a distal end and an elongated tip extending from the distal end having a passageway therethrough in fluid communication with the chamber. A collar surrounds the tip. For the purposes of the present invention collar is intended to include not only continuous structures but also discontinuous structures such as a wall with gaps in its structure. At least one deflectable locking tab projects radially inwardly from the collar and is adapted to engage the hub of a needle assembly to prevent the removal of the needle assembly away from the tip. The locking tab is configured to allow assembly of the needle assembly to the barrel through axial motion of the hub toward the barrel.
Another embodiment of the present fluid transfer device includes a needle assembly having a cannula with a proximal end, a distal end, and a lumen therethrough. A hub includes an open proximal end with a cavity therein and a distal end is joined to the proximal end of the cannula so that the lumen is in fluid communication with the cavity. The hub includes an outside surface. A barrel having a fluid chamber includes an open proximal end, a distal end and an elongated frusto-conically shaped tip extending from the distal end having a passageway therethrough in fluid communication with the chamber. A collar surrounding the tip includes a plurality of deflectable locking tabs projecting radially and proximally inwardly from the collar defining an inner aperture surrounding the tip. The tip extends distally beyond the aperture defined by the locking tabs. The needle assembly is connected to the barrel so that the elongated tip of the barrel is in the cavity of the hub and the outside surface of the hub is adjacent to the inner aperture defined by the locking tabs so that the locking tabs prevent removal of the needle assembly from the barrel through contact between the locking tabs and the outside surface of the hub.
Another embodiment of the present fluid transfer device includes means on the hub between the distal end of the hub and the proximal end of the hub for allowing the hub to break upon application of a bending force to the hub. Such means includes a fracturable section between the proximal end and the distal end of the hub such as an annular discontinuity on the outside surface of the hub or an annular discontinuity in the cavity of the hub. The fracturable section is provided to prevent removal of the needle assembly from the fluid transfer device by allowing the hub to break if an excessive bending force is applied to the hub.
Another embodiment of the present invention includes a plunger having an elongated plunger rod, a proximal portion and a distal portion. The distal portion includes a stopper slidably positioned in fluid-tight engagement with an inside surface of the barrel for drawing fluid into and out of the barrel by movement of the plunger relative to the barrel. The plunger further includes means for allowing the connection between the proximal portion of the plunger rod and the distal portion of the plunger rod to break upon application of additional force to the proximal portion.